Question

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 10⁸ m s⁻¹.

Answer 1

Refractive index of a medium n_m is given by,

`n_m="Speed of light in vacuum"/"Speed of light in the medium" = c/v`

Speed of light in vacuum, c = 3 × 10⁸ m s⁻¹

Refractive index of glass, n_g = 1.50

Speed of light in the glass,  

`v = c/n_g`

`= (3 xx 10^8)/1.50`

`= 2 xx 10^8ms^(-1)`